Optical fibre is increasingly being used for a variety of broadband applications including voice, video and data transmissions delivered to a subscriber's premises. Fibre optic networks typically include a large number of optical fibre joint enclosures (also referred to as Connectorized Lead-in Joints (CLJ)), which provide locations at which one or more optical fibres are branched from a distribution cable to an end user, commonly referred to as a subscriber. Based on the increase in the number of subscribers and the unique physical attributes of optical fibres, optical fibre joint enclosures are needed for making the branches above as well as for protecting and maintaining optical fibres at these fibre branching locations. In particular, optical fibre joint enclosures are needed for readily facilitating connection of optical fibres from a distribution cable to further optical fibres leading to one or more premises to establish desired optical connections. The optical fibre joint enclosure is also requested to provide adequate protection to the branched optical fibres and the optical connections from exposure to environmental conditions.
Typically, the optical fibre joint enclosure is located in an underground pit, and substantial expertise and experience are normally required to configure the optical connections within the optical fibre joint enclosure in the field. In particular, it is often difficult and constrictive to access and work with optical connections inside an optical fibre joint enclosure in the field.
Increasingly, pre-connectorized optical fibres are used in optical fibre joint enclosures for easier interconnection with optical fibres of drop cables extending to subscriber premises. An optical fibre connector terminates the end of an optical fibre and enables quicker connection and disconnection than optical fibre splicing. Two connectors are used in association to align the cores of two optical fibres ends so that light can pass across the join.
In particular, a connector is a mechanical device which is used to align and join together two or more optical fibres thereby providing a means for attaching to, and decoupling from, a fibre optic receptacle, e.g. an optical fibre joint enclosure. Generally, a connector comprises a long and thin cylinder—named “ferrule”—that is bored through the centre thereof so as to contain the optical fibre. The ferrule acts as a fibre alignment mechanism, therefore the optical fibre is inserted into the ferrule in such a way that the end of the optical fibre is located in correspondence of the ferrule end portion.
Typical examples of connectors are SC, FC, LC, ST, E2000 connectors. For instance, FIG. 6 shows a typical SC connector 700. The SC connector is a snap-in connector that is widely used in single mode systems. The SC connector 700 has a substantially square shape and comprises a ferrule 710 which is surrounded by a connector body 720. The SC connector 700 further comprises a latch 730 for allowing safe coupling of the connector to a uniter.
Typically, an optical fibre connector interconnects with a uniter which is a device positioned at the interface between two optical fibre connectors so as to hold the two optical fibre connectors together in alignment. The uniter is also technically known with the term of “adapter” or “adaptor”.
The Applicant has noted that the optical fibre joint enclosures do not provide sufficient space between the base of the optical fibre joint enclosure and the carrier to enable a video-scope probe to be introduced into a uniter end face for inspection of the attached connector end face. Therefore, a typical videoscope for inspection cannot be accommodated with the connectors and uniters in their normal position since no sufficient space is present in the optical fibre joint enclosures.
Currently, when an inspection (for example by using a videoscope) and a cleaning operation of a connector end face (the connector being attached to an optical fibre) housed within an optical fibre joint enclosure has to be carried out, the technician typically needs to remove the connector from the position in which it is physically held within the optical fibre joint enclosure. The connector and associated uniter are held in place by a carrier which mechanically supports the connector and the corresponding uniter. Generally, the carrier is referred to as “uniter patch panel”. The technician removes the connector from the uniter associated to the carrier in order to inspect the connector end face. This operation can place undue stress on the optical fibre due to bending thereof, potentially damaging the optical fibre. There is also a danger that adjacent optical fibres, attached to adjacent connectors held in or by the carrier, can be damaged during removing of the connector which is requested to be inspected/cleaned.
In order to carry out desired inspection or cleaning operations and to provide the necessary space for a correct working and positioning of any testing or cleaning apparatus, the Applicant considered a number of possible technical solutions. For instance, the Applicant thought to increase the size of the optical fibre joint enclosure to allow sufficient access between the base of the enclosure and the carrier for inserting a video-scope or any inspection/cleaning device. However, since a joint enclosure has typically to fit within a relatively small underground pit, if the size of the joint enclosure increases too much, there is not sufficient room in the underground pit to accommodate the joint enclosure.
The Applicant has also thought to angle the carrier to allow for adequate access to the uniters from the front of the joint enclosure. However, according to this solution, the optical fibre cable—that is attached to a connector which is plugged into the uniter during normal operation—would be angled in such a way that the optical fibre cable protrudes outside of the joint enclosure and could be damaged when an exterior joint cap of the joint enclosure is re-installed.
The Applicant has perceived the need of providing a method of inspection of an optical fibre connector which can be advantageously carried out in situ without the necessity of removing the optical fibre connector to be inspected from its seat and, moreover, without causing the adjacent optical fibre connectors—which have not to be inspected—to be disconnected or subjected to any movement (e.g. rotation thereof), thereby avoiding the risk of possible damages of the optical fibres and consequent failure of the optical connection.
The reference in this specification to any prior publication (or information derived from the prior publication), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from the prior publication) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.